Susceptibility-weighted Imaging Sequences Research Articles

Chronic active lesions preferentially localize in watershed territories in multiple sclerosis.

Paramagnetic rim lesions (PRLs) are a biomarker of chronic active lesions (CALs), and an important driver of neurological disability in multiple sclerosis (MS). The reason subtending some acute lesions evolvement into CALs is not known. Here we ask whether a relatively lower oxygen content is linked to CALs. In this prospective cross-sectional study, 64 people with multiple sclerosis (PwMS), clinically isolated syndrome and radiologically isolated syndrome underwent a 7.0 Tesla (7 T) brain magnetic resonance imaging (MRI). The scanning protocol included a T2-w fluid-attenuated inversion recovery (FLAIR), and a single echo gradient echo from which susceptibility-weighted imaging (SWI) was derived. WM lesions were identified on the T2-w-FLAIR whilst PRLs were identified on the SWI sequence. T2-lesions were classified as PRLs and rimless lesions (PRLs-). We registered a universal vascular atlas to each subject's T2-w-FLAIR and classified each T2-lesions according to its location into watershed- (ws), non-watershed- (nws), and mixed-lesion (m). Ws-lesions were defined as lesions that were fully located in a region between the territories of two major arteries. Out of 1,975 T2-lesions, 88 (4.5%) were PRLs. Ws-regions had a higher number (p = 0.005) and proportion (p < 0.001) of PRLs- compared to nws-regions. Ws-PRL- were larger compared to nws-ones (p = 0.009). The number (p = 0.043) and proportion (p < 0.001) of PRLs was higher in ws-regions compared to nws-ones. Ws-PRLs were not significantlylarger than nws-ones (p = 0.195). We propose the novel concept of a link between arterial vascularization and chronic activity in MS by demonstrating a preferential localization of CALs in ws-territories.

Susceptibility-Weighted Imaging for Differentiating Intracranial Calcification and Hemosiderin: A Comparative Study with CT

Background: Magnetic resonance imaging (MRI) is an essential diagnostic modality for evaluating various tissue types, but distinguishing between substances such as calcification and hemosiderin remains challenging due to their similar appearances on conventional MRI sequences. Susceptibility-weighted imaging (SWI) improves tissue contrast by incorporating phase information, potentially enhancing the accuracy of differentiating these substances. This study aims to assess the effectiveness of SWI, specifically the filtered phase image, in comparison with computed tomography (CT), which is considered the gold standard for calcification detection. Methods: A retrospective analysis was conducted on 35 patients, aged 50-80 years, who presented with confirmed cases of intracranial calcification or hemosiderin deposits. MRI was performed on a 1.5-tesla Siemens Essenza Magnetom using SWI sequences, including both phase and magnitude images. CT scans were obtained using a GE Optima 660 scanner. The study focused on 17 cases of calcification identified by both SWI and CT, and 18 cases of hemosiderin deposits detected by SWI. Statistical analysis was performed using Pearson correlation coefficients to evaluate the relationship between MRI and CT measurements. Results: The study revealed a strong correlation between CT and SWI in detecting calcifications, with a significant agreement in the measurement of calcification size. However, while phase and magnitude images demonstrated a strong correlation with one another, the filtered phase image did not show a significant correlation with hemosiderin size, suggesting limitations in its application for detecting hemosiderin deposits. CT scans confirmed calcification with Hounsfield units exceeding 100, while hemosiderin deposits were more effectively identified through SWI, which provided enhanced contrast without the use of ionizing radiation. Conclusion: SWI, particularly the filtered phase image, is a reliable and sensitive tool for detecting intracranial calcification, offering high accuracy compared to CT. While SWI proves effective in distinguishing calcification, further research is needed to optimize its use for detecting hemosiderin deposits. This study underscores the non-ionizing advantages of SWI over CT, advocating for its potential as a safer and equally effective alternative in clinical imaging.

Imaging arterial and venous vessels using Iron Dextran enhanced multi-echo 3D gradient echo MRI at 7T.

Iron Dextran is a widely used iron oxide compound to treat iron-deficiency anemia patients in the clinic. Similar to other iron oxide compounds such as Ferumoxytol, it can also be used off-label as an intravascular magnetic resonance imaging (MRI) contrast agent due to its strong iron-induced T2 and T2* shortening effects. In this study, we seek to evaluate the feasibility of using Iron Dextran enhanced multi-echo susceptibility weighted imaging (SWI) MRI at 7T to image arterial and venous blood vessels in the human brain. Phantom experiments were performed to measure the r2* relaxivity for Iron Dextran in blood, based on which the SWI sequence was optimized. Pre- and post-infusion MR images were acquired in human subjects from which maps of arteries and veins were extracted. The post-contrast SWI images showed enhanced susceptibility difference between blood and the surrounding tissue in both arteries and veins. Our results showed that the proposed Iron Dextran enhanced multi-echo SWI approach allowed the visualization of blood vessels with diameters down to ~100 μm, including small blood vessels supplying and draining small brain structures such as the hippocampus. We conclude that Iron Dextran can be an alternative iron-based MRI contrast agent for blood vessel imaging in the human brain.

GGC repeat expansions in NOTCH2NLC cause uN2CpolyG cerebral amyloid angiopathy.

The expansion of GGC repeats within NOTCH2NLC leads to the translation of the uN2CpolyG protein, the primary pathogenic factor in neuronal intranuclear inclusion disease (NIID). This study aims to explore the deposition of uN2CpolyG as an amyloid in the vessel wall, leading to uN2CpolyG cerebral amyloid angiopathy (CAA)-related cerebral microbleeds (CMBs). A total of 97 patients with genetically confirmed NIID were enrolled in this study. We analyzed the presence of CMBs using susceptibility-weighted imaging sequences and compared general clinical information, cerebrovascular risk factors, stroke history, antiplatelet medication use, and MRI features between NIID patients with and without CMBs. We further performed hematoxylin and eosin (H&E), Perl's, Congo red, and Thioflavin S staining, ubiquitin, p62 and uN2CpolyG immunostaining on brain tissue obtained from four NIID patients. A total of 354 CMBs were detected among 41 patients with NIID, with nearly half located in the deep brain, one-third in the lobes, and approximately 20% in the infratentorial area. No significant differences in cerebrovascular disease risk factors or history of antiplatelet drug use were observed between patients with and without CMBs. However, patients with CMBs suffered a higher incidence of previous ischemic and hemorrhagic stroke events. This group also had a higher incidence of recent subcortical infarcts and a higher proportion of white matter lesions in the external capsule and temporal pole. Conversely, patients without CMBs showed higher detection of high signals at the corticomedullary junction on diffusion-weighted imaging and more pronounced brain atrophy. H&E staining showed blood vessel leakage and hemosiderin-laden macrophage clusters, and Prussian blue staining revealed brain tissue iron deposition. CMBs occurred more frequently in small vessels lacking intranuclear inclusions, and extensive degeneration of endothelial cells and smooth muscle fibres was observed mainly in vessels lacking inclusions. Congo red-positive amyloid deposition was observed in the cerebral vessels of NIID patients, with disordered filamentous fibres appearing under an electron microscope. Additionally, the co-localization of Thioflavin S-labeled amyloid and uN2CpolyG protein in the cerebral vascular walls of NIID patients further suggested that uN2CpolyG is the main pathogenic protein in this form of amyloid angiopathy. In conclusion, we reviewed patients with GGC repeat expansion of NOTCH2NLC from a novel perspective, providing initial clinical, neuroimaging, and pathological evidence suggesting that uN2CpolyG may contribute to a distinct type of CAA.

Could the Anatomic Variants of the Superior Thalamic Vein (STV) Be Considered a Possible Landmark for Target Identification in Magnetic-Resonance-Guided Focused Ultrasound Procedures? A Pilot Study Using Susceptibility Weighted Imaging Sequences.

During magnetic-resonance-guided focused ultrasound ablation of the ventral intermediate thalamic nucleus (VIM) for essential tremor (ET) and Parkinson's disease (PD), targeting is generally performed using a standard atlas-based stereotactic approach. The purpose of our work is to evaluate the anatomic variations in the venous vasculature of the thalamus in patients treated with MRgFUS, as a possible landmark for targeting. We retrospectively evaluated the relationship between the obtained thalamotomy lesion and the ipsilateral superior thalamic vein (STV). A total of 36 patients (25 ET and 11 PD) who underwent MRgFUS treatment were evaluated, and the STV was studied with susceptibility weighted imaging (SWI) sequences. Based on the axial SWI images, the distance between the STV and the center of the lesion at the presumed site of the VIM was measured in follow-up MRI images one month after treatment. Statistical analysis shows that there is a correlation between the STV and the presumed site of the VIM. The STV visible in SWI could be used as an additional, real-time, and patient-specific anatomical landmark for VIM identification during MR examination and just before and during FUS treatment.

Magnetic resonance imaging scanning susceptibility weighted imaging sequences in the diagnosis and prognostic evaluation of neonatal hypoxic-ischemic encephalopathy

BACKGROUND Magnetic resonance imaging (MRI) scanning with susceptibility weighted imaging (SWI) sequences plays a significant role in the diagnosis and prognostic evaluation of neonatal hypoxic-ischemic encephalopathy (HIE). AIM To observe the role of MRI multi-parameter quantitative indexes in the diagnosis of neonatal HIE. METHODS The imaging data from 23 cases of neonatal HIE admitted to the Imaging Department of Ganyu District People's Hospital of Lianyungang City and 23 neonates without HIE admitted during the same period were analyzed retrospectively from August, 2021 to December, 2023. The results of clinical judgment were compared with the results of computed tomography (CT) and MRI examinations. RESULTS The degree of cerebral edema (more than moderate), the number of damaged brain regions (&gt; 2), the number of cerebral hemorrhages (&gt; 2), and the percentage of small venous dilatation detected were higher in MRI than in CT examination, and the differences were statistically significant (P &lt; 0.05). The total area of the largest region of cerebral damage and of cerebral hemorrhage observed by MRI examination were significantly larger than those of CT examination (P &lt; 0.01). Multiparametric quantitative MRI combined with diffusion weighted imaging and SWI had higher sensitivity and accuracy than CT diagnosis, and the difference was statistically significant (P &lt; 0.05). The difference in the specificity of the two modes of diagnosis was not significant (P &gt; 0.05). CONCLUSION The use of MRI multi-parameter quantitative indexes can accurately diagnose and evaluate neonatal HIE.

Correlation between asymmetrical vein sign of SWI and long-term clinical outcomes in patients with middle cerebral artery ischemic stroke.

To evaluate the association of asymmetrical cortical vein sign (ACVS) and asymmetrical medullary vein sign (AMVS) on susceptibility-weighted imaging (SWI) with 90-day poor outcomes in patients with unilateral middle cerebral artery acute ischemic stroke (AIS) after conservative drug treatment. Clinical data for the participants included age, sex, smoking, alcohol, hypertension, diabetes, hyperlipidemia, coronary heart disease, NHISS-admission, and NHISS-discharge scores. Participants underwent magnetic resonance imaging (MRI) within 12h of hospital admission, including conventional scan sequences and a SWI sequence. Poor prognosis was defined as a modified Rankin scale (mRS) ≥ 3 at 90days. A total of 108 patients were included from January 2021 to March 2022. Twenty-seven (25%) patients had a poor outcome at 90days. Univariate analysis indicated that diabetes, NHISS-admission, NHISS-discharge, DWI-ASPECTS, SWI-ASPECTS, FLAIR-ASPECTS, and AMVS + were associated with 90-day poor outcome. Multivariate regression analysis showed that AMVS + was associated with 90-day poor outcome from the three models (OR = 3.57, P = 0.006; OR = 3.74, P = 0.005; OR = 5.14, P = 0.0057). However, no significant association was found between ACVS + and 90-day poor outcome. AMVS might be a helpful neuroimaging predictor for poor outcome at 90days compared to ACVS in drug-conserving treatment of patients with unilateral middle cerebral artery ischemic stroke.

Multi-contrast echo-planar imaging sequence (Echo-planar imaging mix) in clinical situations demanding faster MRI-brain scans.

The excellent resolution offered by magnetic resonance imaging (MRI) has a trade-off in the form of scan duration. The purpose of the present study was to assess the clinical utility of echo-planar imaging mix (EPIMix), an echo-planar imaging-based MRI sequence for the brain with a short acquisition time. This was a retrospective observational study of 50 patients, who could benefit from faster MRI brain scans. The T1, T2, fluid attenuated inversion recovery, diffusion-weighted imaging (DWI), and T2*/susceptibility-weighted imaging sequences were acquired, conventionally and with EPIMix. Conventional and EPIMix images were assessed by two radiologists for overall quality, motion, and susceptibility artifacts and scored on a Likert scale. The scores given for conventional and EPIMix images were compared. The diagnostic performance of EPIMix was also assessed by the ability to detect clinically relevant findings. The acquisition time for conventional MRI was 11 min and 45 s and for EPIMix 1 min and 15 s. All EPIMix images were sufficient for diagnostic use. On assessment of the diagnostic performance, it was excellent for ischemic and hemorrhagic strokes. Smaller lesions, lesions adjacent to bone, and post-operative tumors were difficult to identify. Moderate to perfect agreement (Kappa values 0.41-1) was seen between radiologists for all categories except skull base, calvarial, and orbital lesions. Image quality, artifact assessment showed excellent interobserver agreement (>90%) for the scores. All EPIMix images showed reduced motion artifacts. The EPIMix-DWI was comparable to conventional-DWI in terms of quality and artifacts. The remaining sequences showed reduced quality and increased susceptibility. The EPIMix has a significantly reduced acquisition time than conventional MRI and could be used instead of conventional MRI in situations demanding faster scans such as suspected acute ischemic or hemorrhagic stroke. In other clinical scenarios, it could help tailor the MRI examination for each patient.

Evaluation of diagnostic value of pelvic MRI in endometriosis in comparison with surgical findings: A cross-sectional study.

Endometriosis is a multifocal gynecologic disorder during the fertility period in women. Magnetic resonance imaging (MRI) is an important diagnostic modality for this disease and can either be used alone or along with transvaginal ultrasonography. This study aims to compare the accuracy of pelvis MRI in pelvic deep endometriosis with laparoscopic findings in women referred to Shahid Sadoughi hospital in one year. This cross-sectional study was conducted on 40 women suspicious of endometriosis who referred to Shahid Sadoughi hospital, Yazd, Iran from November 2020-2021. Based on clinical findings and history, participants were referred to the imaging center for pelvic MRI. Finally, the results of MRI and diagnostic laparoscopy were compared with pathologic findings. The sensitivity and specificity of MRI for pelvic endometriosis were 94.8% and 20%, respectively. Also, the positive predictive value and negative predictive value of MRI were 90.2% and 33.3%, respectively. Laparoscopy is still the gold standard of endometriosis diagnosis, but MRI with susceptibility-weighted imaging sequence is the best noninvasive diagnostic method.

Simultaneous time-of-flight MR angiography and quantitative susceptibility mapping with key time-of-flight features.

A technique for combined time-of-flight (TOF) MR angiography (MRA) and quantitative susceptibility mapping (QSM) was developed with key features of standard three-dimensional (3D) TOF acquisitions, including multiple overlapping thin slab acquisition (MOTSA), ramped RF excitation, and venous saturation. The developed triple-echo 3D TOF-QSM sequence enabled TOF-MRA, susceptibility-weighted imaging (SWI), QSM, and R2* mapping. The effects of ramped RF, resolution, flip angle, venous saturation, and MOTSA were studied on QSM. Six volunteers were scanned at 3 T with the developed sequence, conventional TOF-MRA, and conventional SWI. Quantitative comparison of susceptibility values on QSM and normalized arterial and venous vessel-to-background contrasts on TOF and SWI were performed. The ramped RF excitation created an inherent phase variation in the raw phase. A generic correction factor was computed to remove the phase variation to obtain QSM without artifacts from the TOF-QSM sequence. No statistically significant difference was observed between the developed and standard QSM sequence for susceptibility values. However, maintaining standard TOF features led to compromises in signal-to-noise ratio for QSM and SWI, arising from the use of MOTSA rather than one large 3D slab, higher TOF spatial resolution, increased TOF background suppression due to larger flip angles, and reduced venous signal from venous saturation. In terms of vessel contrast, veins showed higher normalized contrast on SWI derived from TOF-QSM than the standard SWI sequence. While fast flowing arteries had reduced contrast compared with standard TOF-MRA, no statistical difference was observed for slow flowing arteries. Arterial contrast differences largely arise from the longer TR used in TOF-QSM over standard TOF-MRA to accommodate additional later echoes for SWI. In conclusion, although the sequence has a longer TR and slightly lower arterial contrast, provided an adequate correction is made for ramped RF excitation effects on phase, QSM may be performed from a multiecho sequence that includes all key TOF features, thus enabling simultaneous TOF-MRA, SWI, QSM, and R2* map computation.

MRI Otak Demensia: Protokol RSUP Dr. Sardjito Yogyakarta

Background: The procedure for examining brain magnetic resonance imaging (MRI) in clinical dementia at the Radiology Installation of RSUP dr. Sardjito Yogyakarta used T2W, 3D FLAIR, 3D FFE ADNI, diffusion weighted imaging (DWI) and susceptibility weighted imaging (SWI) sequences. The selection of this sequence was in accordance with the existing references, but was added with the SWI sequence. This study aims to determine the MRI brain examination in clinical dementia and to find out the reason for the addition of the SWI sequence.Methods: This type of research is a qualitative research with a case study approach. Data was collected by observation, in-depth interviews and documentation. Data analysis was carried out with the stages of data transcription, data reduction, data presentation and carried out discussions and drawing conclusions.Results: The results of the study stated that the measurement of brain volume was carried out by entering the raw data of the T1 FFE ADNI sequence image into the freesurfer software which was useful for assessing Alzheimer's dementia.Conclusions: The diagnosis is made by looking for bleeding and microbleeding using the SWI sequence in assessing vascular dementia. SWI sequences are useful in differentiating between calcification and microbleeding causing vascular dementia.

Prominent Vessel Signs After Endovascular Thrombectomy Corelates with Unexplained Neurological Deterioration and is a More Reliable Imaging Predictor of Prognosis in Anterior Large Vessel Occlusion Stroke

Fifty percent of patients who undergo endovascular thrombectomy (EVT) for large-vessel occlusion exhibit unfavorable outcomes. The primary factor is attributed to persistent brain impairment even after successful EVT. The prominent vessel sign (PVS) on magnetic resonance susceptibility-weighted imaging reflects the territory of dysmetabolism and may facilitate an expeditious assessment for prognostication. We aimed to examine the relationship between PVS after EVT and the occurrence of early neurological deterioration (END) and 3-month outcomes. Patients who underwent EVT and multimodal magnetic resonance imaging were included. END was defined as an increase of ≥2 in the National Institutes of Health Stroke Scale within 72 hours after EVT. Symptomatic intracranial hemorrhage, malignant edema, and surgical complications were defined as definite END, whereas the other symptoms were categorized as unexplained END (ux-END). The PVS-Alberta Stroke Program Early CT Score (ASPECTS) score was used to evaluate the asymmetric cerebral venous signal on the susceptibility-weighted imaging sequences semiquantitatively. A total of 116 eligible patients were included, 18 (15.5%) of whom presented with ux-END. The 72hour National Institutes of Health Stroke Scale was strongly correlated with diffusion-weighted imaging infarct volume and PVS-ASPECTS and was significantly higher in the ux-END group (16 ± 6 vs. 5 ± 4, P= 0.001). The PVS-ASPECTS score was significantly associated with poor outcomes (odds ratio 2.551, 95% confidence interval (CI) 1.722-3.780, P＜0.001), and PVS-ASPECTS (area under the curve 0.884, 95% CI 0.815-0.953, P<0.001) was superior to diffusion-weighted imaging infarct volume (area under the cure 0.720, 95% CI 0.620-0.820, P= 0.001) in predicting 3-month poor outcome. At the optimal cut-off of 2, the PVS-ASPECT predicted poor outcomes with a sensitivity of 89.7% and a specificity of 78.2%. PVS 72 hours after EVT correlated with ux-END. The PVS-ASPECTS is a more reliable predictor of stroke prognosis and provides valuable information regarding post-EVT management.

PERANAN SEQUENCE SWI (SUSCEPTIBILITY WEIGHTED IMAGING) PADA PEMERIKSAAN MRI BRAIN KLINIS PARKINSON

The Role of SWI (Susceptibility Weighted Imaging) Sequence in Clinical Parkinson’s MRI Brain Imaging. Magnetic Resonance Imaging (MRI) is a technique for imaging body crossings based on the principle of magnetic resonance of hydrogen atoms. Brain MRI examination aims to see anatomy and abnormalities within the brain to establish clinical diagnosis, pathological abnormalities, tumors, and surrounding abnormalities. Imaging examinations are also conducted to find other causes of Parkinsonism. Head MRI is one of the non-invasive examinations performed to help confirm the diagnosis of Parkinson's disease. This study aims to determine the procedure for Brain MRI examination with Parkinson's clinical and to determine the sequence information SWI (Susceptibility Weighted Imaging) can establish clinical diagnosis of Parkinson's. This study is qualitative descriptive with a case study approach. The subject consists of three patients with clinical Parkinson's. All subjects performed MRI brain 3 tesla examinations to determine the procedure and sequence information used. The research results were obtained according to the theory using an additional 2 mm sequence, while in the field using 0.9 mm sequence the examination was conducted using the head coil of the patient's position, namely supine, head first. Sequences used in field inspections are AAHead Scout, t1 fl2d transversal, t2 tse (time spin echo) dark fluid transversal, t2 tse (time spin echo) transversal, ep2d diff (diffusion) 4scan trace, asl 3d transversal, tof cs carotids, flow pc3d MRV (magnetic resonance venography), tof brain MRA (magnetic resonance angiography), t2 swi (susceptibility weighted imaging) 3d transversal 0.9 mm. The thin axial sequence of 0.9 mm is more likely to see Parkinson's anatomical abnormalities, higher SNR and better spatial resolution than using a 2 mm slice thickness.

Comparing CT-Like Images Based on Ultra-Short Echo Time and Gradient Echo T1-Weighted MRI Sequences for the Assessment of Vertebral Disorders Using Histology and True CT as the Reference Standard.

Several magnetic resonance (MR) techniques have been suggested for radiation-free imaging of osseous structures. To compare the diagnostic value of ultra-short echo time and gradient echo T1-weighted MRI for the assessment of vertebral pathologies using histology and computed tomography (CT) as the reference standard. Prospective. Fifty-nine lumbar vertebral bodies harvested from 20 human cadavers (donor age 73 ± 13 years; 9 male). Ultra-short echo time sequence optimized for both bone (UTEb) and cartilage (UTEc) imaging and 3D T1-weighted gradient-echo sequence (T1GRE) at 3 T; susceptibility-weighted imaging (SWI) gradient echo sequence at 1.5 T. CT was performed on a dual-layer dual-energy CT scanner using a routine clinical protocol. Histopathology and conventional CT were acquired as standard of reference. Semi-quantitative and quantitative morphological features of degenerative changes of the spines were evaluated by four radiologists independently on CT and MR images independently and blinded to all other information. Features assessed were osteophytes, endplate sclerosis, visualization of cartilaginous endplate, facet joint degeneration, presence of Schmorl's nodes, and vertebral dimensions. Vertebral disorders were assessed by a pathologist on histology. Agreement between T1GRE, SWI, UTEc, and UTEb sequences and CT imaging and histology as standard of reference were assessed using Fleiss' κ and intra-class correlation coefficients, respectively. For the morphological assessment of osteophytes and endplate sclerosis, the overall agreement between SWI, T1GRE, UTEb, and UTEc with the reference standard (histology combined with CT) was moderate to almost perfect for all readers (osteophytes: SWI, κ range: 0.68-0.76; T1GRE: 0.92-1.00; UTEb: 0.92-1.00; UTEc: 0.77-0.85; sclerosis: SWI, κ range: 0.60-0.70; T1GRE: 0.77-0.82; UTEb: 0.81-0.92; UTEc: 0.61-0.71). For the visualization of the cartilaginous endplate, UTEc showed the overall best agreement with the reference standard (histology) for all readers (κ range: 0.85-0.93). Morphological assessment of vertebral pathologies was feasible and accurate using the MR-based bone imaging sequences compared to CT and histopathology. T1GRE showed the overall best performance for osseous changes and UTEc for the visualization of the cartilaginous endplate. 1 TECHNICAL EFFICACY: Stage 2.

Cerebral microbleeds. Utility of SWI sequences

ObjectivesDefine the concept of cerebral microbleeds (CMBs) and describe the most useful MRI sequences for detecting this finding.Review the entities that most frequently present with CMBs and that may benefit from the use of susceptibility-weighted imaging (SWI) sequences. ConclusionsSWI is a useful MRI sequence for the detection and characterization of microhemorrhages, venous structures and other sources of susceptibility in imaging.SWI is particularly sensitive to local magnetic field inhomogeneities generated by certain substances and is superior to T2* GRE sequences for this assessment.CMBs may be seen in different neurologic conditions, in certain infrequent clinical contexts and have a key role as a biomarker status in gliomas (ITTS) and as a marker of inflammatory activity in multiple sclerosis.

Association of brain microbleeds with risk factors, cognition, and MRI markers in MESA.

Little is known about the epidemiology of brain microbleeds in racially/ethnically diverse populations. In the Multi-Ethnic Study of Atherosclerosis, brain microbleeds were identified from 3T magnetic resonance imaging susceptibility-weighted imaging sequences using deep learning models followed by radiologist review. Among 1016 participants without prior stroke (25% Black, 15% Chinese, 19% Hispanic, 41% White, mean age 72), microbleed prevalence was 20% at age 60 to 64.9 and 45% at ≥85 years. Deep microbleeds were associated with older age, hypertension, higher body mass index, and atrial fibrillation, and lobar microbleeds with male sex and atrial fibrillation. Overall, microbleeds were associated with greater white matter hyperintensity volume and lower total white matter fractional anisotropy. Results suggest differing associations for lobar versus deep locations. Sensitive microbleed quantification will facilitate future longitudinal studies of their potential role as an early indicator of vascular pathology.

Cerebral Microbleeds-Long-Term Outcome After Cerebrospinal Fluid Shunting in Idiopathic Normal Pressure Hydrocephalus.

Cerebral microbleeds (CMBs) are common in idiopathic normal pressure hydrocephalus (INPH) and have been suggested as radiological markers of a brain prone to bleeding. The presence of CMBs might be relevant when selecting patients for shunt surgery. To evaluate whether CMBs increases long-term risk of hemorrhagic complications and mortality or affects outcomes after cerebrospinal fluid shunt surgery in a cohort of patients with INPH. One hundred and forty nine shunted patients with INPH (mean age, 73 years) were investigated with MRI (T2* or susceptibility-weighted imaging sequences) preoperatively. CMBs were scored with the Microbleed Anatomic Rating Scale. Patients were observed for a mean of 6.5 years (range 2 weeks to 13 years) after surgery. Hemorrhagic events and death were noted. Improvement in gait was evaluated 3 to 6 months after surgery. At baseline, 74 patients (50%) had CMBs. During follow-up, 7 patients (5%) suffered a hemorrhagic stroke and 43 (29%) suffered a subdural hematoma/hygroma with a median time from surgery of 30.2 months (IQR 50). Overall, having CMBs was not associated with suffering a subdural hematoma/hygroma or hemorrhagic stroke during follow-up with 1 exception that an extensive degree of CMBs (≥50 CMB) was more common in patients suffering a hemorrhagic stroke ( P = .03). CMBs were associated with increased mortality ( P = .02, Kaplan-Meier, log-rank test). The presence of CMBs did not affect gait outcome ( P = .28). CMBs were associated with hemorrhagic stroke and mortality. CMBs do not seem to reduce the possibility of gait improvement after shunt surgery or contribute to the risk of hemorrhagic complications regarding subdural hematoma or hygroma.

Susceptibility artifact morphology is more conspicuous on susceptibility-weighted imaging compared to T2* gradient echo sequences in the brains of dogs and cats with suspected intracranial disease.

Susceptibility-weighted imaging (SWI) has been found to be more reliable in the detection of vessels and blood products than T2*-weighted gradient echo (GE) in several human brain diseases. In veterinary medicine, published information on the diagnostic usefulness of SWI is lacking. The aim of this retrospective observational study was to investigate the value of SWI compared to T2*-weighted GE images in a population of dogs and cats with presumed, MRI-based diagnoses grouped as neoplastic (27), cerebrovascular (14), inflammatory (14), head trauma (5), other pathologies (4), or that were normal (36). Areas of signal void (ASV) were assessed based on shape, distribution, number, and conspicuity. Presence of ASV was found in 31 T2*-weighted GE and 40 SWI sequences; the conspicuity of lesions increased in 92.5% of cases with SWI. A 44.7% increase in the number of cerebral microbleeds (CMBs) was identified within the population using SWI (110) compared to T2*-weighted GE (76). Linear ASV presumed to be abnormal vascular structures, as are reported in humans, were identified in 12 T2*-weighted GE and 19 SWI sequences. In presumed brain tumors, abnormal vascular structures were detected in 11 of 27 (40.7%) cases on T2*-weighted GE and in 16 of 27 (59.3%) cases on SWI, likely representing tumor neovascularization; amorphous ASV interpreted as presumed hemorrhages on T2*-weighted GE were diagnosed as vessels on SWI in five of 27 (18.5%) cases. Since SWI shows ASV more conspicuously than T2*-weighted GE, the authors advocate the use of SWI in veterinary patients.

Value of 3.0T MRI T2 mapping combined with SWI for the assessment of early lesions in hemophilic arthropathy

ABSTRACT Purpose To explore the value of magnetic resonance imaging (MRI) T2 mapping combined with susceptibility-weighted imaging (SWI) in detecting early cartilage damage and joint bleeding in the hemophilic arthropathy (HA). Methods 147 patients and 56 healthy controls were prospectively recruited. The knees were divided into groups A and B according to the criteria of the International Cartilage Repair Society (ICRS). The Regions of Interest (ROIs) of T2 mapping were drawn for the patella, lateral and medial femoral condyle, and lateral and medial tibial condyle. The T2 values were compared between the patients and control group using one-way ANOVA. The joint count data of International Prophylaxis Study Group (IPSG) scores of conventional and SWI sequences were statistically described using the composition ratio, and the rank sum test was used for the difference analysis. Results Finally, there were 99 joints in the control group, 135 knees in group A, and 94 knees in group B. There was a significant difference between the T2 value in each subgroup. Comparison of T2 value groups in each cartilage partition, except for group A and group B of the patella, revealed significant differences (all P<0.05). SWI was likely more sensitive than conventional sequences in detecting hemosiderin deposits in hemophilic joints. In addition, the IPSG scores detected by the SWI were generally higher than those of conventional sequences. Conclusions MR T2 mapping combined with SWI has great potential to be used for detecting early cartilage damage and micro-hemosiderin deposition in hemophiliac arthropathies and developing preventative treatment plans.

&lt;I&gt;In vivo&lt;/I&gt; vascular mapping of the human hippocampus using MICRO imaging

BACKGROUND: There is an urgent need for better detection and understanding of vascular abnormalities at the micro-level, where critical vascular nourishment and cellular metabolic changes occur. This is especially the case for structures such as the midbrain and hippocampus, where both the feeding and draining vessels are quite small. The hippocampus is a complex grey matter structure that plays an important role in spatial and episodic memory. It can be affected by a wide range of pathologies including vascular abnormalities. Being able to monitor vascular changes in normal aging in various hippocampal subfields will allow us to better understand vascular vulnerability across the hippocampus.&#x0D; METHODS: We recently introduced the concept of microvascular in-vivo contrast revealed origins (MICRO) protocol to image micro-cerebral vessels.1-3 MICRO uses ferumoxytol, an ultra-small superparamagnetic iron oxides (USPIO) agent, to induce susceptibility in the arteries and veins; and by imaging with high resolution (0.22×0.44×1 mm3) susceptibility weighted imaging sequence (SWI) at 3 T. Although the increased vascular susceptibility enhances the visibility of small sub-voxel vessels, the accompanying strong signal loss of the large vessels deteriorates the local tissue contrast. Hence, data are collected at different time points during a gradual administration (final concentration = 4 mg/kg) of ferumoxytol. Dynamically acquired SWI data were co-registered and combined (phase gradient-based adaptive combination or SWIPGAC) to reduce the blooming artifacts from large vessels, preserving the small-vessel contrast.&#x0D; RESULTS: The presence of ferumoxytol helped to enhance the microvasculature, something that has previously only been demonstrated in cadaver brain studies. Figure 1 shows the difference between the pre-contrast SWI and SWIPGAC data in visualizing the micro-vasculature across four healthy subjects. The intra-hippocampal and superficial major arteries (obtained through a non-linear subtraction method) and veins (obtained by averaging the T1-shortening map, pre-contrast quantitative susceptibility mapping (QSM) and pre-contrast R2* maps) are used as an overlay in the third column to better visualize the major vessels penetrating and draining the hippocampus. The hippocampal fissure, along with the fimbria, granular cell layer of the dentate gyrus and cornu ammonis layers (except for CA1), showed higher micro-vascular density than the other parts of hippocampus. The CA1 region exhibited a significant correlation with age (R=−0.37, p&lt;0.05, n=37). demonstrating an overall loss of hippocampal vascularity in the normal aging process. Moreover, the vascular density reduction was more prominent than the age correlation with the volume reduction (R=−0.1, p&gt;0.05, n=37) of the CA1 subfield.&#x0D; CONCLUSIONS: With this USPIO-induced increase in susceptibility comes the potential to study the cerebral micro-vasculature using high-resolution SWI. There was a strong negative correlation between hippocampal functional vessel density (FVD) (especially in CA1) and age. This FVD reduction was more prominent than volume reduction vs age, suggesting that vascular atrophy may precede reductions in tissue volume. Mapping the hippocampal vasculature has immediate implications for understanding the effects of normal aging and the etiology of many neurovascular diseases. MICRO imaging brings us into the decade of imaging the microvasculature of the entire human body.